1. Field of the invention
This invention relates to a process for producing methyl formate by dehydrogenating methanol in the vapor phase in the presence of a catalyst of composed copper oxide and a chromium oxide and a sodium compound.
A conventional process for producing methyl formate comprises the esterification of formic acid with methanol, during which a large amount of water is also produced. In the present invention, hydrogen of high purity is produced which can be used as a chemical raw material or as a clean fuel. The selectivity of methyl formate is high and catalyst life is long.
2. Description of the prior art
Prior art processes for producing methyl formate include (a) a process wherein methanol is dehydrogenated in the presence of a catalyst containing copper and cement (U.S. Pat. No. 4,232,171); (b) a process for producing methyl formate where methanol is dehydrogenated over a catalyst produced by reducing a precursor comprising copper oxide and a spinal structure support comprising the oxides of zinc and aluminum, said precursor containing 10 to 80 percent copper. The dehydrogenation temperature is 235.degree. C. to 350.degree. C. (U.S. Pat. No. 4,480,122); (c) a process for producing methyl formate where methanol is dehydrogenated in the presence of a catalyst containing copper and zinc (Japanese patent 53-108916); (d) Japanese patent 54-12315 describes a catalyst containing oxides of copper, zinc and aluminum; (e) Japanese patent 56-7741 describes a catalyst containing copper, zirconium, and calcium; (f) Japanese patent 57-203034 describes a dehydrogenation which is carried out in the liquid phase and in the presence of a catalyst containing chromium.
Among the above-mentioned processes, it appears that in process (a) the conversion of the methanol and yields of methyl formate diminish significantly after running the operation for 24 hours. The process (b) says that the reaction temperatures are about 235.degree. C. to about 350.degree. C., which means if the temperature is below 235.degree. C., the conversion of methanol will decrease significantly, and higher temperature results in a lower selectivity. The processes (c), (d) and (e) teach that the catalyst used is quite different from the catalyst used in the present invention. The process (f) teaches that the reaction is carried out in the liquid phase which means that an additional step of catalyst separation is necessary.